1. Field of the Invention
The present invention relates to a dental instrument adapted to dispense tooth cleaning fluid to a patient's teeth. More specifically, without removing the instrument from the patient's mouth, a tooth cleaning fluid, such as prophylactic paste, is dispensed from the manually controlled instrument to enable the application of the cleaning fluid directly on the patient's teeth while a prophy cup attached to the instrument rotates to clean or polish the surface of the teeth.
2. Description of the Prior Art
The application of tooth cleaning fluid, such as prophylactic paste, to a patient's teeth is a common step in the teeth cleaning process conducted by dentists, oral hygienists, and other dental professionals. Traditionally, a prophy cup attached to a dental instrument is removed from the patient's mouth and dipped into a prophylactic paste-filled container to fill the cup. The dental instrument is then placed in the patient's mouth so that the prophy cup filled with prophylactic paste is pressed against the patient's teeth. A pneumatic actuated mechanism that is connected to the dental instrument then powers the rotation of the prophy cup so that it cleans or polishes the patient's teeth. The paste is used rapidly, thus the instrument must often be withdrawn from the patient's mouth to refill the prophy cup.
Dental instruments that dispense tooth cleaning fluid to a patient's teeth are well known in the art. Such instruments generally include some type of fluid container with a mechanism that is actuated to deliver the tooth cleaning fluid from the container to the teeth and a prophy cup that is rotated by a pneumatic mechanism to which the instrument is connected. The prior art is typically represented by U.S. Pat. Nos. 5,642,994; 7,029,278; 4,266,933; 6,257,886; 2,738,528; 4,220,446; 5,062,796; 3,987,550; 3,775,849; and 2,400,912.
U.S. Pat. No. 2,738,528 shows a handpiece with a flexible tube bent so as to allow the cleaning fluid in a collapsible dispenser to be manually forced through a flexible tube and into a prophy cup. The tube is made of flexible material that makes it prone to kinking. The small size of the tube also results in increased flow resistance and loss of volume. In addition, the collapsible dispenser is anchored to the handpiece by a single strap that can be dislodged when the dispenser is emptying.
U.S. Pat. No. 5,642,994 illustrates a dental instrument with a soft-walled bladder that needs to be anchored to securing pins so that an ellipsoid roller with projections on opposite sides which fit into slots in the retaining walls can be pushed forward to squeeze the tooth cleaning fluid from the bladder and into the prophy cup. Anchoring the bladder to the securing pins is difficult and not effective at holding the bladder in place as the roller squeezes the fluid. Secondly, the roller has small spline on the side projections that are very difficult and expensive to manufacture and difficult for the operator to push since the bladder pushes upward against the roller. This dental instrument is also difficult to use because of the tight space that the roller must squeeze into after anchoring the bladder to the securing pins.
U.S. Pat. No. 4,220,446 requires a secondary pneumatic source for dispensing the cleaning fluid. Furthermore, the cleaning fluid is not dispensed into the prophy cup as desired by dentists, oral hygienists, and other dental professionals. Finally, the bulky design makes it difficult for the operator to insert the tool into a patient's mouth.
U.S. Pat. No. 6,257,886 shows a design where the cleaning fluid is in the same hollow cavity in the housing as the rotating shaft that drives the rotation of the prophy cup. The cleaning fluid has a tendency to stick to the rotating shaft resulting in a slower rotation of the prophy cup. As the rotation of the cup is slowed, it loses its friction function against a patient's tooth required for proper cleaning or polishing of tooth. Additionally, as the shaft rotates, it generates heat within the cleaning fluid that can lead to changes of the properties of the fluid.
U.S. Pat. No. 4,266,933 shows a design where a helical conveyor is rotated to push the cleaning fluid toward the prophy cup. The size of the helical conveyor makes the design too bulky to be easily inserted into a patient's mouth. In addition, the rotation of the helical conveyor generates heat within the cleaning fluid that can change its properties.
U.S. Pat. No. 7,029,278 illustrates a design that does not dispense the cleaning fluid into the prophy cup but adjacent to the prophy cup. Additionally, the plunger that pushes the cleaning fluid toward the prophy cup is not controlled manually by the operator but by a drive member.
U.S. Pat. Nos. 5,062,796, 3,987,550, 3,775,849, and 2,400,912 show designs that require major reconfigurations to the traditional system used. The designs tend to incorporate a pneumatic pressure system for driving the cleaning fluid from a container and into a prophy cup. The major drawback to such design is the retooling that dental instruments already installed would require. Some of these designs even include foot-pedals or other elaborate actuation and control means that unnecessarily complicate the system.